Five things to know about Lindsey Graham

Lindsey Graham will become the ninth Republican to enter the 2016 presidential race Monday when he announces his candidacy in Central, South Carolina, where he was born 59 years ago.

He attended University of South Carolina for his undergraduate degree and stayed on for a law degree. After a stint in the military and a few years of private law practice, he served one term in the South Carolina House of Representatives. Two years later, he was elected to the U.S. House of Representatives, representing South Carolina's Third District. In each of his four elections, he has won more than 60 percent of the vote.

Why Lindsey Graham wants to run for president in 2016

In 2002, he ran for the Senate seat once occupied by Strom Thurmond, and twice won reelection in 2008 and 2014 by robust margins. And even in 2014 when outside conservative groups threatened him with a primary challenge for his role in the 2013 immigration debate, no serious challenger emerged on the Republican stage.

Now, Graham is setting his sights even higher. He's a long-shot candidate, not garnering enough support to make it onto most national polls. In a CBS News/New York Times survey released this week, only 12 percent of Republican voters said they'd consider supporting him for the party's 2016 nomination - the second lowest number of the 14 Republicans included in the poll. 32 percent said they would not consider voting for him, and 55 percent said they don't know. Even in his home state, a Winthrop University poll in April found that 55 percent of likely voters said they would not consider voting for him as president. But with a nearly 60 percent approval rating among likely GOP voters, he could still influence the race.

Here are five things to know about Lindsey Graham:

1. He's one of the GOP's most outspoken hawks: Graham has long been vocal on foreign policy issues, and it's clear that would be a driving force behind a presidential campaign. His political action committee is called "Security Through Strength," a nod to former President Ronald Reagan's slogan, "Peace through Strength."

"Ronald Reagan said 'peace through strength.' I don't think it's possible to peaceably coexist with radical Islam but I do believe it's possible to have security through strength by partnering with people over there so we can keep radical Islam off our shores," Graham told CBS News Congressional Correspondent Nancy Cordes after he announced a testing-the-waters committee for a presidential bid in January.

Sen. Lindsey Graham on 2016: "I'm running because I think the world is falling apart"

"I'm running because I think the world is falling apart. I've been more right than wrong on foreign policy," he said.

Lindsey Graham: "You're gonna need boots on the ground" against ISIS

He is one of the few senators who still advocates for a robust American presence abroad. He believes the U.S. should send about 10,000 military personnel in the country to serve as trainers and support for the Iraqi security forces to recapture territory held by the Islamic State of Iraq and Syria (ISIS).

"We don't have enough military presence on the American side to change the tide of battle," he said.

2. He isn't afraid to clash with members of his own party: Defense is one area where Graham has detractors, particularly among younger members of the GOP like Sen. Rand Paul, R-Kentucky, who believe the U.S. should be more wary about using its military might. But Graham has also shown a willingness to buck Republicans and work with the other side on the issue of immigration.

In 2013, he was part of a bipartisan group of eight lawmakers called the "Gang of Eight" who authored a comprehensive immigration reform bill that passed the Senate but ultimately died in the House. The bill would have ramped up border security and reformed the legal immigration system, and also extended an opportunity for citizenship to immigrants who are currently in the U.S. illegally if they passed a background check, paid taxes, application fees and a fine.

Another Republican member of the "Gang of Eight" who is running for president, Florida Sen. Marco Rubio, ultimately backed away from the comprehensive approach amid a backlash to the bill from both House Republicans and some of the GOP base. Graham did not, and his name was identified with"Grahamnesty" by detractors.

"If I were president of the United States, I would veto any bill that did not have a pathway to citizenship," he recently told USA Today. "You would have a long, hard path to citizenship ... but I want to create that path because I don't like the idea of millions of people living in America for the rest of their lives being the hired help. That's not who we are."

In fact, Graham seems like he would tout his ability to work across the aisle as a credential for his candidacy.

"I've been accused of working with Democrats too much. In my view Democrats and Republicans work together too little and I would try to change that if I got to be president," he said on "CBS This Morning."

GovTrack found that Graham had the second highest score of all senators and highest score among Republican senators for writing bipartisan bills. Sixty-one percent of his bills and resolutions in the 113th Congress had both a Democratic and Republican cosponsor.

He's also shown a willingness to break with Republicans who say humans have not contributed to climate change.

"When it comes to climate change being real, people of my party are all over the board. There was several resolutions," Graham said at a recent Council on Foreign Relations event. "I said that it's real, that man has contributed to it in a substantial way."

He went on to say that the GOP "has to do some soul-searching. Before we can be bipartisan, we've got to figure out where we are as a party. What is the environmental platform of the Republican Party? I don't know, either."

He has an extensive military background: The same day as he announces his run for president, Graham will officially retire from the Air Force Reserves, where he had been promoted to the rank of colonel over his decades of service. He was one of just three senators serving in the Guard or Reserves (the other two are Iowa Sen. Joni Ernst and Alaska Sen. Dan Sullivan, both Republicans).

Before he was elected to Congress, Graham was on active duty from 1982 to 1988, including a four-year posting at Rhein-Main Air Force Base in Germany. From 1989 until 1995, he served in the South Carolina Air National Guard and was called to active duty for state-side service during the first Gulf War. He helped prepare members for deployment at McEntire Air National Guard Base as a Staff Judge Advocate. He joined the Air Force Reserves in 1995.

Graham would frequently travel to Iraq and Afghanistan for short-term reserve duties to work on rule of law issues, even as recently as the last Memorial Day recess for Congress. In 2014, he was presented a Bronze Star Medal for exceptionally meritorious service as a senior legal advisor during Operation Enduring Freedom.

"It's been one of the great honors of my life to serve in the Air Force in some capacity for more than three decades," the senator said in a statement. "The Air Force has been one of the best things that has ever happened to me. It identified and developed my talent, and helped me become useful to my country. It offered me adventure and showed me the world. It gave me a purpose bigger than myself. It put me in the company of patriots. It's been almost like family to me. I'm going to miss it an awful lot, and I wouldn't leave if they weren't making me."

He helped raise his younger sister Darline: Graham's parents died within fifteen months of each other while he was in his early 20s and a student at the University of South Carolina. His sister Darline, who was 13 years old, was left an orphan.

Although Darline went to live with the Grahams' aunt and uncle in Seneca, South Carolina, Graham came home on his weekends during law school to see her. He would eventually become her legal guardian so that she could receive the benefits he got as a member of the Air Force.

Darline - who is now Darline Graham Nordone - talked about her older brother in a 2014 campaign ad.

"It was hard when we lost my mom and my dad. Lindsey assured me that he was going to take care of me and he was going to be there for me and he never let me down. Never," she said. "I don't see how he did it, to take on that responsibility of raising a little sister, that came from within for Lindsey. He always puts other people before him."

His is extremely close to another person who ran for president: Look for Graham in the Capitol and it's all but certain that Sen. John McCain, R-Arizona, is not far behind. The two are close - so close, in fact, that McCain has quipped (multiple times) that Graham is his "illegitimate son."

They are passionate about the same defense issues and even immigration - McCain was one of the Republican members of the "Gang of Eight."

Graham was an active member of McCain's team when the Arizonan ran for president in 2008, and now he seems poised to return the favor for his friend. McCain told reporters back in January that he formally endorsed Graham, months before the actual announcement of a candidacy.

"He's a dark horse--keep an eye on him!" McCain said. "In debates, he'll shred 'em. Have you see ever seen Senator Graham in a debate, on the floor of the Senate? He will do wonderful. I don't want to raise expectations, but I'm confident."